The Federal Bureau of Investigation (FBI) has ordered a Florida medical examiner’s office not to release its autopsy report of a Chechen man fatally shot by an FBI agent in the wake of the Boston Marathon bombings.

The FBI said the reason for holding up the autopsy report was due to the bureau’s active internal investigation into the shooting of Ibragim Todashev, who was killed on May 22 in his Orlando apartment while being interrogated about his connection to Boston bomber Tamerlan Tsarnaev.

What prompted the shooting is still unknown. Some accounts said Todashev attacked the FBI agent with a blade, while others said he was unarmed, and still others said he lunged at the agent with a metal pole or a broomstick.

Todashev reportedly was preparing to sign a confession implicating himself and Tsarnaev, who is now dead, in the 2011 slayings of three men in Waltham.